Edwin j



(mmm E, J. WATSON su H. W. WILLSON.

WATCH SPRING.

No. 266,737. Patented 0013.31, 1882.

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UNITED STATES PATENT OEETCE EDWIN J. WATSON AND HORACE XV. VILLSON, OE WORCESTER, MASSA- CHUSETTS, ASSIGNORS TO THE VASHBURN & MOEN MAN UFACTUl-tINGrY COMPANY, OE SAME PLACE.

WATCH-SPRING.

SPECIFICATION forming part of Letters Patent No. 266,737, dated October 31, 1882.

Application filed May 31. 1882.

To all whom, it may concern:

Bc it known that we, EDWIN J. \VA'1SON and HORACE W. WTLLsoN, both ot' the city and county of 'loi'cester, and Commonwealth of Massachusetts, have invented a certain new made in accordance with theold plan and style practiced prior to our said invention. Fig. 2 represents, also upon an enlarged scale, a ceiltral cross-section of a ywatch-spring embracing our improvement; and Fig. 3 also represents, upon an enlarged scale, a central cross-section of a watch-spring embracing our said invention, but modilied somewhat from the watchspring shown in Fig. 2, as will be hereinafter more fully explained.

The nature of our invention consists of a spring for watches and other similar purposes, one or both sides of which presents convexity in cross section, whereby when the spring is coiled for use. the friction of the spring is reduced to a lninimum, in consequence ofthe convexity of the springpreventingcontact inthe several coils thereof, excepting along the ceutral line of the spring.

To enable those skilled in Ithe art to which our invention belongs to malte and use the same, we will proceed todescribe the invention more in detail.

ln the drawings, Fig. 1, the part marked A represents a section of the old watch-spring, the sides of which are parallel with each other. Fig. 2, B represents a section of a watchspriug embracing our invention, one side, a, of which is made convex, while the other side, a, is made straight; and in Fig. 3,() represents a cross-section of a watch-spring, both sides b of which are convex, as 'fully indicated in thedrawings.

In carrying out our invention the process of (No model.)

manufacture is substantially the same as that described for manufacturing watch-springs in the Letters Patent granted to us January 24, 1882, No. 252,635, and therefore reference is made to such patented process, which obviates the necessity ot' a repetition of the process iu this specilication, and we therefore confine ou i selvesto the statement that wire is used in our present inventirm. and the last reducing operation is carried out by passing the wire or partially-iiuished spring through or between one or more sets of rolls, whereby the sides ol' the spring are left convex, and this result can be obtained by means of rolls having parallel surlaees, as we have demonstrated by actual experiments; but,if preferred, the con vex form ofthe watch-spring may beproduced by other modes of manufacture than that above described without departing' from the principle of our invention.

As before stated, watclrvsprings thus made, as above indicated, aie more perfect in action, in consequence of the slight friction existing between the several coils of the springa result which has been long sought alter, but which has not been attained prior to our said invention. Any .suitable process may be adopted in carrying out our invention.

lt will be understood by those skilled inthe art to which our invi ntion belongs that.- a watch'spriug convex only upon one side will possessalmostthe sameadvantages as a watchspring convex upon both sides, and therefore wedo not limit ourselves to a watch-'springconvex on both sides; but

\Vhat we claim as our invention, and desire to secure by Letters Patent, is-

As an improved article of manufacture, a watch-spring convex upon one or both sides, substantially as and forthc purposes set forth.

EDWIN J. VATSON. HORACE \V. \V.ILLSON.

Witnesses:

EDWINVE. MOORE, GrrAs. D. GAY. 

